Circuit interrupter



Feb. 10, 1942. R. LuDw|G ErAL 2,272,380

CIRCUIT INTERRUPTER INVENTOR Feb. 10, 1942.

1|.. R. LUDWIG Erm.

' CIRCUIT INTERRUPTER Filed Jan. l5, 1940 2 Sheets-Sheet 2 l ATTOPatented Feb. 10, 1942 UNITED STATE sl PATENT OFFICE CIRCUIT-INTERRUPTER Application January 13, 1940, Serial No. 313,736

24 Claims.

This invention relates to improvements in circuit interrupters and, moreparticularly, to circuit breakers of the air break type wherein an arcestablished between separable contacts is extinguished by a blast of airor other suitable gas. Compressed air has been recognized as a suitablearc extinguishing medium by the electrical engineering profession forsome time. Particularly in European countries, considerable progress hasbeen made in the development of circuit breakers of this type. Thisdevelopment, however, has led tothe almost universal adoption of thelongitudinal blast interrupter wherein the stationary contact isarranged in the form of a nozzle at the end of a pressure chamber inwhich the arc is drawn. Compressedair is admitted to the pressurechamber and blasts the arc principally along its longitudinal axis inorder to bring about arc extinction.

Although the longitudinal blast type of interrupter is fairly eicient atlow interrupting capacities, it has armarked disadvantage at highinterrupting capacities since the amount of air required to effectivelyextinguish the arc increases rapidly with an increase in current. Thusit appears that the interrupting capacity of the longitudinal blast typeof interrupter has a practical upper limit which is principallydetermined by the maximum practical air pressure available.

We have discovered that the extinction of an arc by directing a blast ofair crosswise of the arc is less dependent upon the air pressureemployed. It has been found that moderate air pressures, such as 150pounds per square inch, are sufficient when employed in conjunction witha properly designed arc extinguishing structure to interrupt as high as66,000 amperes at 13,200 volts, whereas an interrupter of thelongitudinal blast type would require air pressures many times thisvalue.

The main object of our invention is to improve the interrupting ability-of gas blast circuit breakers without resorting to high gas pressures.In accomplishing this object, particular attention has been given to themethod of treatment of the arc in the presence of a cross blast of gas,which method contemplates utilizing the gas blast morel eiectively toquickly remove the ionized gas particles from the arc stream so as torender the inter-contact space non-conducting in the short interval oftime during which the arc current passes through zero.

Further in obtaining our improved results, we have recognized the valueof spaced arc splitter plates arranged edgewise of the path of the arcand against which the arc is driven by the laterally directed blast ofgas. It is a known fact that (by the use of gas forming material in thearc splitter plates, such as fiber, arc extinction particularly at thehigher values of current, is enhanced. Attempts have been made toutilize fiber arc splitter plates in an arc extinguishing device,wherein the arc is drawn in a narrow throat-like air blast passagedisposed in front of the splitter plates. Although this form ofinterrupter is elective at low and medium values of current,interruption at high currents is diicult, if not impossible. The reasonfor the failure of this type of device to interrupt on the highercurrents is believedv to be that the action of the arc upon'the -bersplitter plates generates gas in such quantities to create a localpressure suliicient to block the air blast and thereby prevents theremoval of ionized gas surrounding the arc.

Consequently a quantity of ionized gas is trapped in back of the arcstream as it has no mean-s of escape other than through the arcitself,"which is at the source of the locally generated pressure. Thus,when the arc passes through current zero, the accumulated ionized gasmust be expelled which results in a cannonlike detonation and often isthe cause of failure of the extinguisher to interrupt because of thcpresence of excessive ionized gas in the intercontact space.

A further object of our invention is to provide an arc extinguishingstructure of the aforesaid type employing spaced gas forming arcsplitter plates, but in which provision is made for sweeping away theionized arc gases surrounding the arc substantially as quickly as thesegases are formed, to thereby make the intercontact space non-conductingat the first current zero. The particular structure whereby thisimproved result is obtained depends upon the arc chamber configuration,as well as the method of directing the air blast upon the arc stream,and will be specically described hereinafter.

Our invention further contemplates improving the interrupting ability ofa gas blast interrupter of the cross blast type by confining the arc toa slot-like passage in the 'arc splitter plates and arranging theseplates so that they diverge from each other in the direction of gas flowin order that more accurate control of the' arc may be obtained. Theconverged or arc receiving ends of the splitter plates are closelyspaced and tapered so as to obtain uniform spacing therebetween, thusavoiding a change in spacing as the plates erode due to frequent circuitinterrupting operations.

It is also an object of our invention to improve the interruptingabilityy of a gas blast circuit breaker of the aforesaid type by theprovision of means for limiting the arc length which consequently limitsthe arc voltage and arc energy which must be dissipated during theinterrupting operation.y

Another object of our invention resides in the improvement of thecircuit interrupting ability of gas blast circuit breakers by theprovision of a more effective treatment of the ionized gases driven fromthe arc stream 4by the blast of 'compressed gas. In this connection, ithas been observed that in an arc chute provided with fiber arc splitterplates, a greater volume of gas is generated by the arc at the side ofthe arc chute adjacent the stationary contact. This gas must be allowedto escape freely and uniformly from the space surrounding the arc and atthe same time must be cooled sulficiently so that an arc will not reformacross an ionized path at any point along the length of the splitter.

To obtain a uniform flow of gas between the arc splitters, the splittersare arranged with a decreasing degree of divergence from the stationarycontact side of the arc chute in the direction of movement of themovable contact. The arc gases driven into the arc chute must also besufficiently cooled and deionized by the time they reach the exhaust endof the chute so that reignition across the ends of the splitter plateswill not take place.

It is a further object of our invention to provide adequate cooling ofthe hot arc gases driven through the spaces between the arc splitters bythe use of metallic cooling elements which are desirable in that they donot throw off more uncondensable gas under the influence of hightemperatures. It is also found desirable to shape the cooling elementsin such manner that the hot arc gases are deected away from the arcsplitter plates, thereby further decreasing the gas generation along thesplitter plates.

Our invention also has for its object the proper spacing of the metalliccooling elements along the arc splitter plates in an endeavor todecrease the velocity of the ionized gas so as to obtain the maximumcooling elect incident to long time exposure of the gas to the coolingelements but without decreasing the velocity of the gas to such anextent that excessive back pressure is obtained. We have also found thatgreater efliciency is obtained by exposure of the individual coolingelements to the same amount of heat which has led us to provide a largernum ber of cooling elements in the gas discharge spaces between thesplitter plates adjacent the stationary contact than in the remainingspaces, and also to make the cooling elements more numerous at theexhaust ends of the gas discharge spaces since the time of exposure tothe gas is materiallygreater at the exhaust end than at thegas receivingend of the spaces.

Other objects and advantages will be apparent from the followingdescription when taken in connection with the accompanying drawings, inwhich Figure 1 is an elevational view showing the circuit interrupter ofour invention;

Fig. 2 is a sectional view taken longitudinally of the circuitinterrupting unit of the circuit interrupter shown in Fig. 1; and

Fig. 3 is a sectional view of the circuit interrupting unit of Fig. 2,taken at right angles thereto and along the line III-III of that figure.

Referring to the drawings, the reference number 5 designates a frame forsupporting a tank 1 in which gas, such as air, may be stored underpressure. The upper side of the pressure tank 1 is provided with aflanged outlet conductor 9 upon which is 'mounted a hollow insulator II.Mounted upon the upper end from the hollow insulator II is an arcextinguishing unit generally indicated at I3. The arc extinguishingunit, as more clearly shown in Fig. 2, includes a stationary contactassembly I5 comprising a plurality of yieldingly mounted contact fingersI1 supported in a box-like compartment I9 disposed between the two sidewalls 2I of the arc extinguishing unit. The side walls 2| are preferablyof insulating material and cooperate with the end walls 23 and 25 toform a ilared are chute, as shown. The wall 25 joins a wall 21 so as todefine one narrow side of an arc chamber. Opposite the wall 21 is a.wall 29 which joins the box-like structure I9 housing the stationarycontact assembly I5. lThe walls 25 and 21 are pro vided with a slot-likeaperture 3| through which blade-like moving contact 33 is adapted tomove to coact with the contact fingers I1 of the sta tionary contactassembly I5. The moving contact 33 is mounted for pivotal movement at 35to a bracket 31 clamped about the hollow insulator II. The bracket 31 isof conducting material and is provided with an extension 39 which servesas a terminal to which external circuit connections may be made. Thestationary contact assembly I5 is provided with a similar terminal 4Ifor also making connection to the external circuit. Thus, when themoving contact 33 is in engagement with the contact fingers I1, anelectrical circuitis established through the interrupter from theterminal 4I, the contacts I1, moving contact 33, conducting bracket 31to the terminal 39.

Operation of the moving contact 33 to the open and closed circuitposition is effected by an air actuated mechanism 43 supported from theside of the pressure tank 1. The lmechanism 43 includes a piston (notshown) operable within the cylinder 45, which piston is connected by arod 41 to a bell crank 49 pivotally mounted at 5I. The bell crank 49 iscoupled by a link 53 to the movable contact 33. Thus, when the pistonrod 41 is actuated downwardly to rotate the bell crank 49 in acounterclockwise direction, the moving contact 33 will be moved to theopen circuit position, and similarly when the piston rod 41 is movedupwardly, the moving contact 33 will be moved to the closed circuitposition.

Air to operate the mechanism 43 to open and closed circuit positions isadmitted to the cylinder 45 by valves 55 and 51, respectively. Thecontrol of these valves may be effected in any conventional form anddoes not constitute a part of the present invention. The bell crank 4!is also provided with a cam mechanism 59 which actuates a pivoted rockerarm 8| which, in turn, operates a spring closed valve 63 disposed in the:flanged conduit 9 extending above the pressure tank 1. The valve 63controls the flow of air from the tank 1 into the hollow insulator II.The passage through the insulator I I is provided with a gas directingnozzlev G5 at the upper end thereof which extends into the entranceportion of the arc extinguishing unit I3 defined by the end walls 21 and29 and the lower sides of the two side walls 2|. Thus, as the valve 63is moved to the open position, a blast of air will be released from thetank 1 through the insulator Il into the arc extinguishing unit 3between the contacts I1 and 33. Opening movement of the valve 63' takesplace both during the opening and closing operation of the contact 33,thus the cam means 59 is normally inoperative to open the valve 63 wherethe moving contact 33 is in thefully open or closed position. However,during movement from one position to the other, the valve 63 is openedto' admit the required blast of gas to extinguish the arc.` Inasmuch asthe specific 'contact structure, the operating mechanism including thecam means 59 and the air blast control valve 63 are not a part of thisinvention but are more fully disclosed and claimed in the application ofA. H. Bakken Serial No. 313,745 led January 13, 1940, and assigned tothe assignee of this application, it is not deemed necessary to furtherdescribe such mechanism. Inasmuch as our invention is particularlydirected to the arc extinguishing structure of a circuit breaker, thesame will now be specifically described.

As previously mentioned, the side walls 2| and thel Walls 23 and 25 forman arc chute for extinguishing the arc formed between the contacts |1and 33. The lower end of the arc chute is provided with a pair of liningmembers 61 disposed along the inside walls of the walls 2| so as toprovide a narrow passageway 69 of generally rectangular cross section.The slot-like opening 3| in the walls 25 and 21 communicates with thepassageway'69 and is preferably disposed centrally thereof. The passage69 from a point substantially opposite the midpoint of the contact 33,diverges rapidly to a. width as that shown at 1|. Disposed between thewalls 2| are a plurality of arc splitter plates 13 preferably ofmaterial which gives off gas when acted upon by an arc such as fiber.The plates 13 are preferably supported along their side edges in groovesprovided for that purpose disposed on the inner surface of the walls 2|.The lower end of the arc splitted plates 13 are adapted to be receivedby suitable slots formed in the lining member 61, as more clearly shownin Fig. 3. The arc splitter plates 13' are also provided with a U-shapednotch or slot 15 extending inwardly from the lower end thereof so as toform a passageway through which the moving contact 33 may operate.

It will be noted that the lower ends of/the splitter plates 13 aretapered for a distance somewhat greater than the length ofthe notches 15so as to provide spaces 11 of uniform width between the ends of theplates. It will be seen that by making the spaces 11 of uniform width,the spacing will not be affected by erosion of the plates 13 as a resultof action of the arc thereon. Disposed above' the notches 15 and in thespaces between the plates 13 are a plurality of short plates 'i9 ofconducting material. .A single plate 19 is preferably symmetricallypositioned between two adjacent plates 13 and, for example, may be heldin position by having their side edges recessed in the lining members61. The plates 19 are preferably tapered, as shown, and have their loweredges curved for the purpose of offering less resistance to the flow ofgas therearound. The purpose of the plates 19 will appear more fullyhereinafter. Also disposed in the spaces between the arc splitter plates13 are a plurality of metallic cooling elements 9| which may be formedof perforated sheets of metal or metallic screening bent in the formshown and secured to bolts 93 extending transversely through the femanating from the nozzle G5.

side walls 2|. The cooling elements 8| will also be more fully describedin connection with the operation of the arc extinguishing structure.

The* operation of the circuit interrupter is, as

follows. Upon separation of the contacts |1 and 33, an arc is drawn inthe notches 15 of the plates 13. At the same time, a blast of air isadmitted by the valve 63 through the insulator Il and throtlgh thenozzle 65 into the passage 69. The air is preferably maintained at sucha pressure that it is injected into the passage 69 at a high velocity,preferably the velocity of sound so that it will not normally bedeflected or caused to follow the divergence of the side walls of thepassage. The air stream thus strikes the arc and drives it to the endsof the notches 15 and causes the arc to elongate somewhat between thearcsplitter plates 13. Further arc looping between the splitter plates13 is prevented as a result of the presence of the cooler plates 19. Ifa 1ow current arc is being interrupted, very little gas generation willtake place as a result of the action of the arc upon the splitter plates13 and the air blast through the nozzle 65 will continue to drive theionized gas particles surrounding the arc against and around themetallic plates 19. The metallic plates 19, in addition to serving asbuffers to prevent excessive elongation of the arc, also serve ascoolers to initially cool the hot arc gases. As the arc gases passbeyond the buffer plates 19, they encounter the metallic coolingelements 8| disposed between the splitter plates which further cool anddeionize the gases and bring about complete deionization of the gases inthe discharged spaces between arc splitters and thereby prevent theissuance of flame from the upper or open end of the arc chute. In theevent that a heavy current arc is drawn, considerable gas may-begenerated as a result of action of the arc upon thev splitter plates 13.The generation of this gas,

Aif not excessive, is beneficial in aiding extinction of the arcprovided proper means are at handto duickly remove the ionized gasessurrounding the arc. The pressure resulting from the gas generated byaction of the arc on the splitter plates 13 may become suflicient tocompletely block the high velocity stream of air The air blast from thenozzle 65 would normally be ineffective to sweep the ionized gas outfrom in back of the arc in the event the arc were held confined in anarrow throat-like passage. It will be noted with particular referenceto Fig. 3 that the notches 15 will generally control the position of thearc and permit it to be moved upwardly a short distance into the rapidlydiverging portion of the arc chute, as defined by the'portion 1| of thelining member 61. Thus there is adequate space between the sides of thearc and the lining members 1| for the ionized arc gases to be blown toeither side of the arc and into the spaces between the arc splitterplates 13.

to interrupt the circuit. Thus, the particular arrangement of the slotstructure in the splitter plates for positioning the arc with respect toan arc passage of predetermined width, permits the air blast directedagainst the arc to remove the ionized gases surrounding the arcsubstantially as quickly as these gases are formed and thus insureprompt circuit interruption at the first current zero. 'i

In practice, we have found that in a circuit interrupter which iscapable of interrupting 66,000 amperes at 13,200 volts, a slot width ofapproximately l1/ inches and a length of approximately 3 'nches in thesplitter plates 13 is suitable when used in conjunction with an airblast passage 69 having a width of approximately 2 inches, and whichstarts to diverge at a point approximately 11/2 inches from the closedend of the notches 15. The preferred amount of divergence of the airblast passage is from 2to approximately 7 inches for a longitudinallength of approximately 21/2 inches.

A further improvement in the interrupting ability of our arcextinguishing structure is obtained by directing the blast o1 air fromthe nozzle G into the gas blast passage 69 at an angle with respect tothe vertical longitudinal axis thereof.

As more clearly shown in Fig. 2, the nozzle 65 extending into theinsulator I l has a discharge opening of generally circular crosssection and its longitudinal axis generally in alignment with theright-hand arc splitter plate 13 so that the gas blast is directedgenerally to the end oi the arc formed adjacent the stationary contactI1. Directing the blast of gas towards the stationary contact rendersthe interrupter more eflloient during the interruption of both light andheavy currents. During interruption of the circuit, the arc will beextinguished before appreciable contact separation has taken place ifthe current zero occurs at that time, in that the gas blast is directedupon the section of arc immediately adjacent the stationary contact. I nthe event the current zero occurs after appreciable contact separation,the arc gas generation, particu; larly at high currents, as a result ofaction of the arc upon the splitter plates 13, will cause an intensepressure to be generated at or near the stationary contact I1 as soon asthe arc is drawn, which pressure will also cause the gas blast from thenozzle 65l to be deflected to the left towards a lower pressure area.Thus, the intense local pressure at or near the stationary contact,instead of blocking the air blast and preventing it from removing theionized gas quickly will cause the air blast to deflect and carry withit the ionized gases from in back of the arc into the gas dischargespaces between the arc splitter plates towards the left-hand side of thearc chute.

It is-thus seen that by directing the air blast at an angle to thegeneral longitudinal axis of the air passage provides for more rapidclearing of the inner contact space of ionized gas and, therefore,improves the arc extinguishing ability of the interruptor.

It has been previously mentioned that more intense local gas pressuresare generated at or near the stationary contact. This is due largely tothe fact that as the arc is drawn from the stationary contact throughthe notches 15 inthe successive arc splitter plates 13, the first platescontacted by the arc will have been subjected to the action of the arcfor a longer period of time than those last contacted. In other words,the heating elect upon the splitter plates will diminish in thedirection of movement of the moving contact 33. It, therefore, followsthat the gas discharge spaces between the splitter plates to theright-hand side of the arc chute must discharge greater volumes of gasthan those towards the left-hand side of the arc chute. In order tomaintain a more uniform iloW of gas which is essential to proper coolingand deioniz ing the gases, the splitter plates 13 are not uniformlyspaced as shown. That is, the degree of divergence of the platesdecreases progressively in the direction of movement of the movablecontact.

It has previously been mentioned that the ci ficiency of the interrupteralso largely depends upon its ability to quickly cool and deionize thearc gases driven into the gas discharge spaces adjacent the arc splitterplates. In this connection, it will be noted with particular referenceto Fig. 2, that the cooling elements 8l are made more numerous in theregion of the exhaust portion of the arc chute whereas they are moresparse at the entrance portion of the gas discharge spaces. Thisarrangement is provided in order to subject each cooling element tosubstantially the same amount of heat and also to avoid decreasing thevelocity of the discharged gas to such an extent as would causeexcessive back pressure. This is based upon the theory that the coolingeffect oi the metallic cooling elements is proportional to the time ofexposure to the hot gases. It will be apparent that as the arc gases arecooled, their velocity is decreased and also as the space in which thegases are discharged increases in volume, the velocity will alsodecrease. Therefore, in order to maintain uniform cooling effect perunit length of gas travel between the arc splitter plates, onlyrelatively few units can be placed in the lower end of the spaceswhereas an increasing number per unit length may be advantageouslyemployed towards the exhaust end of the gas discharge spaces.

4lt will Valso be noted that the right gas disc arge space is requiredto conduct gases from the/arc stream of higher temperature than thegas'in the discharge passages between the remaining passages. In orderto keep the cooling effect more uniform through the entire arc chute aprogressively smaller number of metallic cooling elements 8l areemployed in the gas discharge spaces in a direction from the righthandto the left-hand side of the arc chute.

A further improvement in the circuit interrupting performance of ourdevice is obtained by shaping the cooling elements 8|, as shown, so thatthey present a concave surface facing the source of the arc gases. Thisparticular arrangement has the advantage that it deflects the hot arcgases away from the arc splitter plates 13, thereby preventing thefurther formation of gas during movement of the gas through the gasdischarge spaces.

.Although we have shown and described a speciflc circuit interruptingstructure and in certain instances have given specific dimensions and apreference for certain materials, it is to be understood that the sameis for the purpose of illustration and' that changes and modificationsmay be made by those skilled in the art without departing from thespirit and scope of the appended claims.

We claim as our invention: 1. In a gas blast circuit interrupter,relatively movable contacts for establishing an arc, means ldefining apassage for directing a blast of gas transversely of the arc gap formedupon separation of said contacts, the side walls of said passagediverging rapidly in a' direction laterally of the arc in the region ofcontact separation, means causing a blast of gas to flow through saidpassage of velocity suflicient to prevent substantial divergence of thegas stream at the diverging portion of said passage during the existenceof relatively small current arcs, and partition members at leastpartially of gas forming material disposed in spaced relationtransversely of said passage and having their ends extending close toAsaid arc gap, said blast of gas driving the arc against the ends ofsaid partition members, said partition members having the ends thereofagainst which the arc is driven positioned in the widened portion of thediverging passage and producing gas under pressure during the existenceof relatively high current arcs and causing said gas blast to bedeflected to either side of the arc at the widened portion of saiddiverging passage and sweep the ionized gas out of said passage. l

2. In a gas blast circuit interrupter, an arc chute having a relativelynarrow entrance portion, an exhaust portion and an intermediate portionwhich rapidly diverges in width laterally of the arc towards saidexhaust portion, relatively movable contacts separable at leastpartially in said widened intermediate portion to establish an arc, aplurality of spaced plate members of insulating material extendingacross said arc chute within said exhaust and said intermediateportions, and means for directing a high velocity blast of gas into saidentrance portion to drive said arc against the ends of said platemembers, said plate members having anA inwardly extending notch whereinsaid arc is adapted to play, said notches having a width less than thewidth of said intermediate portion at the notches to hold the arc outofengagement with the sidewalls of said chute and permit said blast of gasto sweep the ionized gas substantially as quickly as formed from theintermediate portion of the arc chute to the exhaust portion thereof. y

3. In a gas blast circuit interrupter, means defining a relativelynarrow passage, spaced plate means at least partially of gas formingmaterial extending across said passage, contact means for drawing an arctransversely of said passage adjacent and across the ends -of said platemeans, and means directing a blast of gas of high velocity into saidpassage to drive the arc against the ends of said plate means, said gasdirecting l means being aimed to cause said blast of gas to playprincipally upon a relatively short first formed section of the arc andto flow in almost a straight line out of the gas directing means andthrough the space between said plate means adjacent said short sectionof arc.

al. In a gas blast circuit interrupter, an arc chute having an entranceportion and an exhaust portion, separable contact means for establishingan arc transversely of said entrance portion, a plurality of spaced arcsplitter plates arranged across said arc chute edgewise with respect tothe path of the arc, and means directing a blast of gas of high velocityinto said entrance portion for moving the arc against the edges of saidsplitter plates, said gas blast distraight line from the gas blastdirecting meansl through the rst space adjacent said end of the arc,said splitter plates comprising material which gives oil gas when actedupon by an arc and being adapted when subjected to relatively largecurrent arcs to cause the gas given off to be directed principallythrough the remaining spaces between said splitter plates for quicklydriving the ionized gases to the exhaust portion of the arc chute.

5. In a gas blast circuit interrupter, an arc chute having a constrictedentrance portion and an exhaust portion, said arc chute diverging inwidth laterally of the arc from said entrance to said exhaust portion,separable contact means for establishing an arc transversely of said arcchute, a plurality of spaced are splitter plates disposed across saidarc chute and arranged edge- Wise 'with respect to the path of the arc,said splitter plates having the edges thereof engaged by the arcpositioned in th'e widened portion oi the arc chute,andnozzlemeansfordirecting ahigh velocity blast of gas into the entranceportion of said chute for moving the arc against the edges of saidsplitter plates, said nozzle means directing said blast of gassubstantially upon one end 0f said arc and causing said blast to exhaustprincipally through the spaces between the splitter plates adjacent saidend of the arc during the extinction of relatively small current arcs,said splitterk plates being composed at least in part of gas formingmaterial which when subjected to relatively large current arcs generatesgas in sufficient quantities to deect said gas blast both around thesides of the arc and into the lspaces between the remaining splitterplates for sweeping the arc path of ionized gases.

6. In a gas blast circuit interrupter, an arc chute having an lentranceportion and an exh'aust portion, a plurality of spaced partitionsarranged across said chute, said partitions diverging from the entranceportion toward the exhaust portion of the chute and being provided Witha U-shaped notch at the converged ends thereof, relatively movablecontacts for establishing an arc in said notches, and means fordirecting a blast of gas transversely of said arc to drive it againstthe closed ends of said notches, the converging ends of said partitionsbeing tapered to provide uniform spacing therebetween for a distance atleast equal to the length of said arc receiving notches.

7. In a gas blast circuit interrupter, an arc chute having an entranceportion and an exhaust portion, a plurality of spaced partitions ofinsulating material arranged across said chute, said partitionsdiverging from the entrance portion toward the exhaust portion of saidchute and having a, slot at the converged ends thereof, means forestablishing an arc in said slots, means for directing a blast of gasinto the entrance portion of said chute to move the arc toward theclosed ends of said slots, and metallic plate means disposed in spacedrelation to said partitions in the diverging spaces between saidpartitions and extending adjacent the closed ends of said slots forlimiting movement of the arc between said partitions in th'e region ofsaid slots and for cooling the arc gases.

8. In a gas blast circuit interrupter, an arc chute having a throat-likeentrance portion and a flared exhaust portion, spaced arc splitterplates of insulating material arranged across said chute to divide thechute into a plurality of gas discharge passages, said arc splitterplates extending from said throat portion to adjacent the exhaust end ofsaid chute and having arc receiving slots adjacent said throat portion,5

means for establishing an arc in said slots, means for directing a blastof gas into said throat portion to drive the arc to the end of saidslots, and plates of conducting material arrangedacross said chute insaid gas discharge passages and extending adjacent but not to the closedends of said slots to provide terminals for the are and preventexcessive lengthening of the arc beyond said slots.

9. In a gas blast circuit interrupter, an arc chute having a throat-likeentrance portion and a flared exhaust portion, spaced arc splitterplates of insulating material arranged across said chute to divide thechute into a plurality of gas discharge passages, which increaseprogressively in cross section toward said exhaust portion, said arcsplitting plates having arc receiving edges adjacent said throatportion, means for establishing an arc adjacent said edges, means forblowing a blast of gas into said throat portion to force the arc toagainst said edges, and plate means of conducting' material arrangedacross said chute in the ilared gas discharge passages and extending towithin a relatively short distance of said edges for preventingexcessive looping of the 'arc into said gas discharge passages, saidarc'splitter plates being composed at least in part of a material whichgives off gas when acted upon by an arc, said plate means of conductingmaterial being spaced from the arc 3 splitter plates on each sidethereof and permitting said blast of gas to sweep the ionized gases fromaround the arc into the flared exhaust portion of the arc chute alongeach side of each' of said plate means of conducting material.

10. In a gas blast circuit interrupter, an arc chute having an entrancevportion and an exhaust portion, a plurality of partitions `extendingacross said chute and arranged to diverge from each other in a directiontoward said exhaust portion, means for drawing an arc across theconverged ends of said partitions, and means for directing a blast ofgas into said entrance portion for moving the arc against the ends osaidpartitions, said partitions being progressively more closely spaced inthe direction in which said arc is drawn to provide gas discharge spacesbetween adjacent partitions which are approximately proportional to thequantity of gas to be dischargedA therethrough during each circuitinterrupting operation.

11. In a gas blast 'circuit interrupter, an arc chute having an entranceportion and an exhaust portion, a plurality of arc splitting plates ofinsulating material extending across said chute and being arranged todiverge from each other in'a direction toward said exhaust portion,means for drawing an arc across the converged ends of said partitions,means for injecting a blast oi' gas into said entrance portion to drivethe arc against the ends of said arc splitting plates, vand a pluralityof metallic cooling elements disposed across each of the spaces betweenadjacent arc splitting plates for cooling and deionizing the arc gasesdischarged through said 7 spaces, said cooling elements being morenumerous per unit length along said plates in a direction toward saidexhaust portion.

12. In a gas blast circuit interrupter, an arc chute having an entranceportion and an exhaust 75 portion, a pluralityv of arc splitting platesoi' insulating material arranged in diverging relation across said chutewith their converged ends adjacent the entrance portion thereof todivide said chute into a plurality of gas discharge passages, said arcsplitting plates having a progressively decreasing degree of divergencefrom one side of said chute to the other, means for establishing an arcacross the converged ends of said plates, means for subjecting said arcto a lateral blast of gas, and a plurality or metallic cooling elementsdisposed across eachI of said passages, said cooling elements being morenumerous in the discharge passages of greater divergence and also morenumerous in each discharge passage at the exhaust portion than at theentrance portion in order to provide a maximum cooling eiiect withoutcreating excessive back pressure in each of said passages.

13. In a gas blast circuit interrupter, an arc chute, a plurality ofpartitions or insulating material extending across said chute to divideit into a plurality of gas discharge passages, means for establishing anarc across one end of said partitions, means subjecting said arc to alateral blast of gas, said blast of gas driving the ionized gas from thearc stream into said gas discharge passages, and cooling means disposedin said passages for cooling and deionizing said arc gases, said coolingmeans comprising a plurality of curved perforated metallic platesdisposed with their concave sides facing the flow of gas through saidpassages and positioned at spaced intervals along said passages, saidcurved metallic plates defiecting the hot arc gases away from saidpartitions to avoid further formation of gas by the action of the hotarc gases on said partitions.

14. In a gas blast circuit interrupter, means defining a relativelynarrow passage, spaced plate means of insulating material extendingacross said passage, contact means for drawing an arc in said passageadjacent and generally normal to the ends of said plate means, and meansfor directing a high velocity blast of gas against the arc at an anglewith respect to the longitudinal axis of the arc for moving the arcinclined toward the first-formed section of the arc against the ends ofsaid plate means and subjecting a relatively short first-formed sectionof the arc to substantially the full effect of said blast.

15. In a gas blast circuitg'interrupter, an arc chute having an entranceportion and an exhaust portion, a plurality of spaced partitions ofinsulating material arranged across said chute, said partitionsdiverging from the entrance portion toward the exhaust portion of saidchute, means for establishing an arc in a direction generally normal tothe converging ends of said partitions, means for directing a blast ofgas into the entrance portion of said chute to move the arc against theconverging ends of said partitions, and buier plates of conductingmaterial and of substantially less length than said partitions disposedin the diverging spaces between said partitions adjacent but spaced fromthe converging ends thereof, said buier plates acting to confine the arcin the region of the converging ends of said partitions.

16. In a gas blast circuit interrupter, an arc chute having an entranceportion and an exhaust portion, a plurality of spaced partitionsarranged across said chute, said partitions diverging from the entranceportion toward the exhaust por tion of the chute, relatively movablecontacts for establishing an arc across the converging ends of saidpartitions, and means for directing a blast of gas laterallyl of said-arc to drive it against the ends of said partitions, the convergingends of said partitions being tapered to provide uniform spacingtherebetween at least in the region of ar-c engagement.

17. In a gas blast circuit interrupter, an arc chute having an entranceportion and an exhaust portion, a plurality of arc splitting plates of`1nsulating material arranged in diverging relatlon across said chutewith their converged ends adjacent the e. trance portion thereof todivide said chute into a plurality of gas discharge passages, said arcsplitting plates having a progressively decreasing degree of divergencefrom one side of said chute to the other, means for establishing anarcacross the converged ends of sa1d plates, means for subjecting saidarc to a late ral blast of gas, and a plurality of metallic coolingelements disposed across eachof said passages.

18. In a gas blast circuit interrupter, an arc chute in which an arc maybe established, said arc chute having a constricted entrance portion,v

an exhaust portion and a portion widened laterally of the arc betweenthe constricted entrance portion and the exhaust portion,.spacedpartition members in the arc chute having at least portions adjacent thepath where the arc is established of insulating material which gives offgas when acted upon by the arc, means causing gas under pressure to flowinto the arc chute through the constricted entrance portion and blow thearc against the edges of said partition members, and said edges of thepartition members against which the arc is blown being in said widenedportion of the arc chute.

19. In a gas blast circuit interrupter, an arc chute in which an arc maybe established, said arc chute having a constricted entrance portion, anexhaust portion and a portion widened laterally of the arc between theconstricted entrance portion and the exhaust portion, spaced partitionmembers in the arc chute having at least portions adjacent the pathwhere the arc is` established of insulating material which gives off gaswhen acted upon by the arc, means causing gas under pressure to flowinto the arc chute through the constricted entrance portion and blow thearc against the edges of said partition members, said edges of thepartition members against which the arc is blown being in said widenedportion of the arc chute, and means for holding the arc againstsubstantial lateral movement in said widened portion of the arc chuteand directly in the concentrated blast of gas from the constrictedentrance portion.

20. In a gas blast circuit interrupter, an arc chute, a movable contactfor drawing an arc therein, said arc chute having a narrow entranceportion, a portion widened in a direction transversely of the arc, andan exhaust portion, said movable contact having at least one edgemovable in said widened portion of the arc chute a plurality ofinsulating members positioned in the arc chute and having edge portionsextending closely adjacent to the path of movementof said edge of thecontact movable in the widened portion of the arc chute, a source of gasunder pressure connected to cause a blast of gas through the narrowentrance portion of the arc chute, and means preventing transversemovement of the arc in said widened portion of the arc chute and holdingthe arc in the concentrated blast Iof gas from said narowentranceportion.

, 21. In a gas blast circuit interrupter, an arc chute in which an arcmay be established, said arc chute having a constricted entranceportion, an exhaust portion and a portion widened laterally of the arcbetween the constricted entrance portion and the exhaust portion, spacedpartition members of insulating material in the arc chute and havingnotches adjacent the path where the arc is established, means causinggas under pressure to flow into the arc chute thnough the constrictedentrance portion and blow the arc toward the closed ends of the notches,said closed ends of the notches lying in said widened portion of the arcchute and restricting lateral movement of the arc in said widenedportion so as to hold the arc in the path of the concentrated blast ofgas through the constricted entrance portion of the arc chute.

22. In a gas blast circuit interrupter, an arc chute having an entranceportion and an exhaust portion, a plurality of spaced partitionsarranged across said chute, said partitions diverging from the entranceportion toward the exhaust portion of the chute, relatively movablecontacts for establishing an arc adjacent the converged ends of saidpartitions, means supplying a blast of'gas through the entrance portionof the chute for driving the arc against the converged ends of thepartitions, and said converged ends of the partitions being of reducedthickness to facilitate ilow of said blast of gas into the exhaustportion of the chute.

23. In a gas blast circuit interrupter, an arc chute having an entranceportion and an exhaust portion, a plurality of spaced partitions ofinsulating material arranged across said chute, means for establishingan arc adjacent the edges of said partitions of insulating materialnearest the entrance portion of the chute, means supplying a blast ofgas through the entrance portion of the chute to move the arc againstsaid edges of said partitions of insulating material, and metal platespositioned between said partitions of insulating material and generallyparallel therewith, said metal plates extending adjacentto but beingspaced away from the edges of said partitions of insulating materialagainst which the arc is moved by the blast of gas.

24. In a gas blast circuit interrupter, an arc chute, a plurality ofpartitions of insulating material extending across said chute to divideit into a plurality of gas discharge passages, means for establishing anarc across one end of said partitions, means subjecting said arc to alateral blast of gas, said blast of gas driving the ionized gas from thearc stream into said gas discharge passages, and cooling means disposedin said passages for cooling and deionizing said arc gases, said coolingmeans including a plurality of metallic members permitting flow of gasthereover and having inclined surfaces deflecting the hot arc gases awayfrom said partitions to retard Athe further formation of gas by theaction of the hot arc gases on said partitions.

LEON R. LUDWIG. HERBERT L. RAWLINS. BENJAIVIIN P. BAKER.

